Is there a well-established naming convention for PHP namespaces?

Question

So far, I've seen many different naming conventions used for PHP namespaces. Some people use PascalCase\Just\Like\For\Classes, some use underscored\lower_case\names, some even use the Java convention for package names: com\domain\project\package.

The question is very simple -- can any of these (or other) conventions be called well-established? Why? Are any of them recommended by authorities like Zend or the developers of well-known PHP frameworks?

Answer 1

A PHP Standards Working Group made up of contributors to many different PHP frameworks and projects came up with the following proposal for appropriate namespace usage:

https://github.com/php-fig/fig-standards/blob/master/accepted/PSR-0.md

Answer 2

I don't think you can say there is anything well established at this point, but there is an RFC discussing it for PEAR2: http://wiki.php.net/pear/rfc/pear2_naming_standards

My take is that namespaces are a form of variables, and therefore should follow the same convention as they do. I genereally prefer lowercase_underscore for free variables (As opposed to object members), so the most natural for my taste would be namespace\ClassName. This also matches the most prevalent conventions from other languages. On the other hand, the same argument could be made for pre-5.3 pseudo-namespaces, but here the de-facto standard seems to be using CamelCase.